The present invention relates to a process and to an apparatus for the display of relief moving pictures. It is used more particularly in the transmission of moving pictures on a network (switched, broadcasting, broadband, etc) and in particular in visiophony, i.e. in telephony accompanied by the bilateral transmission of pictures. The invention is also used in the formation of relief moving pictures in simulation systems, video games, etc, in which the pictures are produced from informatics means.
A considerable amount of research has already been carried out on the formation of relief moving pictures, particularly television pictures. However, the hitherto conceived solutions have not given rise to satisfactory realizations, because they all suffer from serious disadvantages. The best known of these, which is similar to a solution envisaged for cinematography, consists of providing the televiewer with special spectacles, whereof the two different lenses make it possible to see on the receiver screen two different pictures representing the images which are respectively perceived by the right eye and the left eye of the observer. This need for the viewer to wear spectacles is naturally a serious handicap, which has hampered the development of this method.
Another solution is described in FR-A No. 1,543,994, granted on Sept. 23, 1968, for "An integral relief, colour television process and apparatus". Use is made therein of two orthogonal frames, both when shooting and when reconstructing the picture. On shooting, the first frame is a lenticular relief analyzing frame and comprises juxtaposed vertical cylinder lenses with a concave diopter. These lenses produce a plurality of images in their focal plane. The second frame is a lined color selection frame, which is placed in the focal plane of the lenticular system. The shooting camera consequently analyzes a doubly framed image. On reception, a first horizontal frame is constituted by phosphor lines with alternating colors, these lines making it possible to reconstruct a picture in color. A second frame formed by juxtaposed vertical cylindrical lenses with a convex diopter is placed in front of the first. The viewer then sees the picture in color through the lenticular frame, which restores the relief.
Such a system suffers from the disadvantage of using a cathode ray tube, whose scanning is not sufficiently stable for the picture elements formed on the tube screen to be correctly aligned and permanently behind the optical separator. Thus, there is a sufficiently serious relief loss to dissipate any interest in the system.
Another solution is described in French Patent Application FR-A No. 2,400,812 entitled "Three-dimensional television picture reproduction apparatus". Once again, it involves the use of a lenticular frame, but the latter is attached to a matrix-type, flat-faced screen forming two overlapping pictures, one being seen by the right eye and the other by the left eye. Although this apparatus is satisfactory in certain respects, the observation conditions for the thus formed pictures are not completely satisfactory.
The research carried out by the present inventors on this subject has provided a better understanding of the origin of these difficulties. It has been found that the observing comfort could be considerably improved by breaking with certain prejudices of the prior art, the first of them consisting of transferring the structure of the screen onto that of the lenticular frame on which it rests. In particular, in the last-mentioned specification, the spacing of the screen is always equal to that of the lenticular frame. However, surprisingly, the present inventors have found that this was one of the causes of the poor results obtained and that the pictures observed had a better quality if the spacing of the image formed behind the lenticular frame was larger than that of the frame.